A magnetostrictive linear position sensor is a type of transducer that measures the position of an object along a linear path. It relies on the principle of magnetostriction, which refers to the property of certain materials to change their shape in response to the application of a magnetic field.
The basic components of a magnetostrictive linear position sensor include:
Waveguide: The waveguide is a long, slender tube made of magnetostrictive material, such as nickel or iron. It serves as the sensing element and is typically installed along the length of the object whose position needs to be measured.
Magnet: A small permanent magnet is usually mounted on or inside the object whose position is being measured. The magnet creates a magnetic field in the vicinity of the waveguide.
Interrogation or Excitation Pulse: The sensor system generates an electrical pulse, which travels along the waveguide as an ultrasonic strain wave. This pulse is often referred to as the "interrogation" or "excitation" pulse.
Sensing Pulse: When the interrogation pulse encounters the magnetic field generated by the magnet (which is attached to or within the object), it experiences a change in its velocity. This change is proportional to the distance between the magnet and the position where the interrogation pulse meets the magnetic field. This modified pulse is referred to as the "sensing pulse."
Detection System: There are different ways to detect the sensing pulse, but a common method is by using a sensing coil surrounding the waveguide. As the sensing pulse passes through the sensing coil, it induces a voltage in the coil. This induced voltage is then measured and processed to determine the time of flight of the sensing pulse.
Electronic Processing Unit: The voltage signal generated by the sensing coil is processed by an electronic unit. By measuring the time of flight between the interrogation pulse and the sensing pulse, the distance between the magnet and the sensing element (waveguide) can be calculated accurately. This distance corresponds to the position of the object being measured along the linear path.
The key advantage of magnetostrictive linear position sensors is their high accuracy, repeatability, and resistance to various environmental factors. They can be used in a wide range of applications, such as industrial automation, automotive systems, aerospace, and robotics, where precise and reliable position measurement is essential.